The cerebellum is assumed to play a major role in the pathophysiology of essential tremor (ET). As intention tremor is considered one of the classical features of cerebellar disease, we have assessed a large group of patients with ET for the semiology of the tremor and have performed objective quantitative analysis of a grasping movement in patients with ET, cerebellar disease and a normal control group. We found 25% of the patients to have a moderate or severe kinetic tremor with clear-cut features of a classical intention tremor. Another 33% of the patients had a mild intentional component of their kinetic tremor. Patients with intention tremor (ET(IT)) did not differ from those with predominant postural tremor (ET(PT)) with respect to alcohol sensitivity of the tremor and the frequency of a family history. ET(IT) patients were older and more often showed head and trunk involvement. The onset of this intention tremor has been assessed retrospectively. It was found to begin at a randomly distributed time interval after the onset of the postural tremor, but older patients had a shorter time to development of intention tremor. Quantitative accelerometry of postural tremor showed similar tremor frequencies in both patient groups, but ET(IT) patients had a slightly larger tremor amplitude. Quantitative analysis of a grasping movement using an infrared-camera system was performed in two subgroups of the patients with ET(PT) and ET(IT) and control groups with cerebellar disease or normal subjects. The intention tremor could be quantified objectively as an increased amplitude of curvature during the deceleration and target phase of the movement. The amplitude measurements of intention tremor were clearly abnormal and of comparable magnitude for ET(PT) and cerebellar disease. Additionally, the patients with ET(IT) had a significantly slowed grasping movement during the deceleration and target period. Hypermetria was significantly increased for the patients with ET(IT) and cerebellar disease. We conclude that intention tremor is a feature of ET. ET(IT) patients have abnormalities of their upper limb function compatible with cerebellar disease. This suggests that patients with more advanced ET show abnormalities of cerebellar functions.

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Objective: A third of people over 65 years experiences at least one fall a year. The Timed Up-and-Go (TUG) test is commonly used to assess gait and balance and to evaluate an individual’s risk of falling. Approach: We conducted a clinical study with 46 older participants for evaluating the fall risk assessment capabilities of an ultra-sound based TUG test device. The fall protocols over a period of one year were used to classify participants as fallers and non-fallers. For frailty evaluation, state-of-the-art questionnaires were used. Fall recordings were compared to six TUG test measurements that were recorded in fallers and non-fallers. Main results: TUG test data were available for 39 participants (36 f, age 84.2 ± 8.2, BMI 26.0 ± 5.1). Twenty-three participants did fall at least once within the fall screening period. We fitted two different regression and probability models into a region of interest of the distance over time curve as derived from the TUG device. We found that the coefficient of determination for Gaussian bell-shaped curves (p < 0.05, AUC = 0.71) and linear regression lines (p < 0.02, AUC = 0.74) significantly separated fallers from non-fallers. Subtasks of the TUG test like the sit-up time showed near significance (p < 0.07, AUC = 0.67). Significance: We found that specific features calculated from the TUG distance over time curve were significantly different between fallers and non-fallers in our study population. Automatic recording and analysis of TUG measurements could, therefore, reduce time of measurements and improve precision as compared to other methods currently being used in the assessments of fall risk.

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The resulting images revealed the tips of individual stereocilia of living sensory cells of the organ of Corti and the typical shape of the ciliary bundle. Scanning electron-microscopic (SEM) images of the identical hair bundles obtained after AFM investigation demonstrated that up to four AFM manipulations on the same cell did not cause obvious damage to the surface morphology of the stereocilia.

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